Drainage means for floating tank roofs



J. H. WlGGlNS 2,718,976

DRAINAGE MEANS FOR FLOATING TANK ROOFS 2 Sheets-Sheet 1 Sept. 27, 1955 Filed Oct. 31, 1950 FIG.|.

INVENTOR.

JOHN H. W/GEINS, 2 BY 2,

ATTORNEY I Sept. 27, 1955 Filed Oct. 51 1950 J. H. WlGGlNS 2,718,976

/2/ qr s 2f 5 16 m 5% G T? INVENTOR,

JOHN H. WIGGINS.

A TTORNE 3.

United States Patent 0 DRAINAGE MEANS FOR FLOATING TANK ROOFS John H. Wiggins, Chicago, Ill.

Application October 31, 1950, Serial No. 193,199

4 Claims. (Cl. 220-26) This invention relates to floating tank roof drains of the general type that comprise a hinged or collapsible lower portion composed of one or more sections of metal pipe, joined at its lower end to the bottom of the tank in such a manner that it can swing upwardly and downwardly, or distend and collapse, so as to accommodate the rise and fall of the roof, and a flexible, tubular member that joins the upper end of said hinged or collapsible lower portion to a sump on the top surface of the floating roof.

One object of my present invention is to provide a novel floating tank roof drainage means of the general type above referred to, whose component parts are of such construction and arrangement that the roof can move downwardly and come to rest on the bottom of the tank during the operation of emptying the tank, without danger of crushing or imposing a destructive load on said drainage means.

Another object of my invention is to provide a floating tank roof drain of the general type above referred to, whose component parts are so constructed and arranged that during the rise and fall of the roof, the flexible, tubular connection between the roof and the hinged or jointed lower pipe portion of the drain will assume a predetermined shape or form, and moreover, will not be subjected to stresses that result in rapid deterioration of same.

And still another object of my invention is to provide a novel floating tank roof and a drainage means for same, that overcomes the necessity of cutting the bottom of the tank or forming a housing in said bottom, to receive the drainage means when the roof is in its extreme lower position, resting on the bottom of the tank. Other objects and desirable features of my invention will hereinafter be pointed out.

To this end I have devised a gravity drain for floating tank roofs that has the following features and characteristics which distinguish it from conventional drains of the general type or kind previously referred to:

(a) The roof has a flexible or limber portion disposed in such relationship with the component parts of the drain that when the roof approaches the bottom of the tank, a means that is connected to or carried by the roof or the tank bottom or the drain, causes the said flexible portion of the roof to flex into such a position that when the roof finally comes to rest on the bottom of the tank, no portion of the roof contacts with or rests upon the drain;

(b) The flexible, tubular member which constitutes the connection between the roof and the lower pipe portion of the drain is attached to said parts in such a way that a considerable portion of the flexing of said tubular member which is utilized or relied upon to provide for relative movement between the roof and the pipe portion of the drain, is attained by twisting or imparting torsional movement to said tubular member andspreading said torsional movement throughout the length of said tubular member, thereby reducing deterioration of same; and

(c) The previously mentioned portion of the roof that is flexed so as to make for the drain when the roof comes to rest on the bottom of the tank, is provided with a sump having a downwardly inclined bottom surface that leads from a low point on the roof at which rain water collects, and extends a considerable distance to an outlet for the sump, which, at all times, is located in a plane lower than the said low point on the top surface of the roof at which rain water collects.

In the accompanying drawings which illustrate one form of my invention,

Figure l is a fragmentary top plan view, partly broken away, showing the position assumed by the co-acting parts of the drain when the roof is in its lowermost position, resting on the bottom of the tank;

Figure 2 is a fragmentary, vertical sectional view, taken on the line 2-2 of Figure 1, showing by solid lines how the weight of the roof is prevented from being imposed on the drain when the roof is resting on the bottom of the tank, and showing by broken lines the position assumed by the torsional member of the drain before the lower pipe portion of the drain starts to rise with the roof;

Figure 3 is an enlarged vertical sectional view of the sump on the roof, taken on its long axis, showing by solid lines the position assumed by said sump when the roof is floating on the liquid in the tank, and showing by broken lines, the position assumed by the sump when the roof is resting on the bottom of the tank; and

Figure 4 is a fragmentary, vertical sectional view, taken on the line 44 of Figure 1, showing by solid lines the position assumed by the drain members just before the pipe portion of the drain starts to rise with the roof, and showing by broken lines the position assumed by said pipe portion when the roof is nearly at the top of the tank.

In the drawings, the reference character A designates the side wall of the tank, B designates the bottom of the tank, C designates an annular pontoon that constitutes the peripheral portion of the roof, D designates the deck portion of the roof which is attached to said annular pontoon, E designates a circular pontoon attached to said deck portion so as to constitute the central portion of the roof, and F designates a sump that is formed in the deck portion D. My improved drain is used to conduct rain water from the sump F to an outlet at the lower end'of the tank formed by a vertical pipe 2 in the tank bottom attached to a horizontally-disposed discharge pipe 1 that is located underneath the tank bottom in a concrete trench or housing 20, as shown in Figures 2 and 4. Said drain is suspended from the deck portion D of the roof, and is so constructed that when the roof rises and falls during the operation of filling and emptying the tank, said drain will not impede or interfere with the vertical movement of the roof. Briefly described, said drain comprises:

(a) One or more sections of metal pipe hinged to the bottom of the tank or combined in such a way as to produce an articulated or jointed conduit, whose upper end portion swings about a horizontal axis during the rise and fall of the roof; and

(b) A flexible, tubular member that constitutes a connection between the sump F in the deck portion of the roof and the upper end of the pivoted or rockable part of the previously mentioned pipe portion of the drain.

During the operation of emptying the tank the'drain collapses or folds onto the bottom of the tank, and in order that the roof may also come to rest on the bottom of the tank without crushing the drain or causing the weight of the roof to be imposed on the drain, means is provided for maintaining a flexible or limber part of the deck portion D located directly above or in the zone of the drain, in spaced relation with the bottom of the tank when the roof is in its lowermost position, Hence,

in a floating tank roof equipped with a gravity drain em- 3 bodying my invention, it is essential (a) that the roof beprovide'd with a flexible part located directly above or in the zone of the co-actingmembers of the drain, and (b) that the roof, or the tankbottorn, or the drain memhere be provided with abutment devices so' arranged that when the roof comes to rest on the bottom, said abutmer t deyices'will'. cause the said flexible part of the roof tofle'xin a. direction to prevent the" roof from contacting with or beari'n'gupon the co-acting members of the drain. In. the preferred form' of my invention herein illustrated, the lower pipe portion of the drain is composed of two pipes 4 and 6 arranged in parallel relation, as shown in Figure l, and joined together at one end by a conventional swing joint 5, that permits the pipe 6, which for convenience I will refer to as a swing pipe, to rock on" a horizontal axis. The other end of the pipe 4- is joined to theoutlet 2 in thebot tom of the tank by a swing joint 3, and the other end of the" pipe 6 is connected with the sump F in the roof by a flexible, tubular member 9 formed preferably by a hose or equivalent conduit that is capable of flexing laterally intermediate its ends, and also'capableof torsional movement producedlby rotating one end of the member 9 about its longitudinal axis while the opposite end of said member 9 is prevented from turning, or, in other words, is held against rotary movement. Usu'ally, the hose 9, which, for convenience, I will refer to as the torsional member of the drain, is attached'to the pipe 6 by a pipe elbow 7 provided with a flange 8, said elbow 7 being disposed so that the hose 9 projects laterally, at approximately right angles, from the swing pipe 6. The opposite end of said hose 9' is attached to the sump F in the roof by a pipe 11 rigidly connected to a vertically-disposed: end wall 14 of the sump, asshown" in Figure}, said pipe 11 being provided with a rigid flange that is rigidly fastened to a flangeoh" the end of, the'torsional'member 9, (see Fig. 3) so as to holdsaid torsional member against rotary movement,

as hereinafter explained. Thus, it will be seen that the parallel pipes 4 and 6 form a collapsible conduit whose lower end is hinged to the bottom of the tank and whose upper end is'joined to the sump in roof by a hose 9, one end of which is rigidly attached to the sump and the other end of which is disposed at approximately right angles to and attached to a member (the pipe 6) that swings in an arc during the rise and fall of the roof. Said, collapsible conduit is suspended from the roof by a chain l2or equivalent flexible supporting device whose upper end is preferably fastened to the roof in proximity toaman-hole 13 in the deck portion of the roof.

The sump F is of novel form and preferably consists of a relatively long and narrow box or depression in the flexible deck portion D of the roof, provided with an end wall' 14 disposed substantially vertically with relation to the top'surface of said deck portion, and provided with a bottom wall 15 that leadsfrom a low point 22 on the top surface of the roof at which rain water collects, and extends several feet distant (5 feet to 15 feet) to the outlet pipe 11 in the end wall. of the sump. A sump of the particular form above described is desirable, in that the relatively deep discharge portion of same comprising the end wall 14, strikes against the bottom of the tank during the final portion of the downward movement of the-roof and causes the limber deck portion'of' theroof toflex upwardly sufliciently' to prevent the weight or load of the roof from being imposed on the co-acting mem bers of the drain which rest on the bottom of the tank,

asshown in Figure 2. Subsequently, when the roof-rises,

the bottom.wall 15 of thesump assumes its former or normal position, wherein said bottom wall is sloped downwardly at asufliciently sharp angle to insure eflicient discharge of rain water from the sump into the discharge outletof. the pump In Figure 3 the solid lines indicate the slope or angle of the bottom Wall 15 of the sump whenthe roof is floating. on the liquid in the tank, and' the brokenlines indicate the slope or angle-of-said 4 bottom wall when the roof is at rest on the bottom of the tank.

It is not essential that upward flexing of the deck portion of the roof suflicient to prevent the drain members from being crushed or damaged when the roof comes to rest on the bottom of the tank, be attained by constructing the sump so that it has a relatively deep discharge end portion of greater depth or height than the intake end portion of the sump. Various means may be used to produce or cause such flexing of the deck of the roof without departing from the spirit of my invention. For example, stools or abutment members 16 on the bottom of thetank can be used to prevent the deck portion of the roof from contacting with or bearing upon the drain members when the roof is resting on the bottom of the tank, or the drain members may be provided with pipe flanges 21 of such diameter that they serve as abutment members that support the flexible part of the deck in thezone of the drain members when the roof is resting on the tank bottom.

When the roof is floating the sump F takes the position shown in' solid lines in Figure 3, and in broken lines in Figure 2. Note that there is a good slope from 22 to 11 when floating. The sump may hit the tank bottom or an abutment thereon before the rest of the roof is clear down. Then as the roof descends a few more inches, the sump flexes the portion D of the roof upwardly and takes the'broken' line position in Figure 3 and the solid line position in Figure 2.

The operation of the pipes 4 and 6 with chain 12 is self-explanatory. But note in Figure 4 that the flange 8' connected to the torsional member 9 has rotated through angle 17 which twists member 9 that many degrees of are which torsion is substantially equally distributed throughout the length of torsional member 9. Note before 8 has been moved upwardly at all that 9 in Figure 2' is almost straight, which is the best position for torsion' to spread this torsion throughout its length andreduce deterioration of member 91 This straight position of 9 before it is twisted is attained by placing the ends of member 9 in a vertical plane, which is at the large angle 19, Figure l, to the plane of movement of the pipes. D of the roof, when 9 ceases vertical movement relative toflange 8, is suchthat 9is' nearly straight.

In Figure 1 the angle 23 is the angle which controls which side of the linebetween 8and'10'that the'member 9 will lie-when roof descends;

length of the member 9 (about 130"), is such that 9 can only take a single loop, as shown in Figure 1, due to its inherent stiffness, and hence, can never cross itself and p'robably be injured by the deck D'of the roof coming down on it when the roof comes'to rest on the bottom of the tank.

From the foregoing, it will be understood that one of the novel and distinguishing characteristics ofmy im- 7 proved drainis that the pipe portion of the drain is connected with the sump'in the roof'by a'flexible coupling member 9 combined with said parts in such a way that during the rise and fall ofthe roof the flange 8 at' one endof said coupling'mernber' passes through-arc 17, and hence, twists the member 9 or rotates it about its'longitudinal axis while the opposite end of said member 9 (the end provided with the flange 10) is held against rotary movement. In this way, I utilize torsional movement of the member 9, in addition to lateral flexing of said member, to accommodate or compensate for relative movement between-the roof and the upper end of the hinged or jointed pipe portion of the drain during the operation offilling and emptying the tank. I

The fact-that the two faces of the flanges 8 and 10 are disposed at only a slight angle to each other is desirable, in that it puts the hose 9 in the best position fol-twistingor torsional movement, and hence, prolongs the-life of In addition, the amount of the rise of the deck I The relationship of the' horizontal'distance between Sand 10 (say 86") to the same, but the actual twisting of the hose is effected by rotating one end of the hose about its longitudinal axis while the opposite end of said hose is held against rotary movement. In my improved drain the axes of the opposite ends of the hose 9 are disposed at a horizontal angle with each other so that when the roof descends low enough, the hose 9 will flex on the same side of the projection of the line between the two ends of said hOSe in such a way that the hose can never cross itself, and moreover, will not accidentally come into contact with the means employed to flex the deck portion of the roof into a position to protect the component parts of the drain from injury. Also my improved drain is desirable, in that it overcomes the necessity of cutting the bottom of the tank or forming a housing in same to receive the drain members when the roof is resting on the bottom of the tank.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. The combination of a tank adapted to hold liquid, a floating roof in said tank constructed and arranged so as to rest upon and be directly supported by the bottom of the tank when the tank is emptied, at least a portion of the roof normally contacted by the liquid in the tank being limber, a sump carried by the limber portion of the roof and provided with a downwardly inclined bottom whose upper end is at all times substantially flush with a surface on the top side of the roof at which rain Water collects and whose lower discharge end is normally located at a level substantially lower than the said water collecting surface on the top side of the roof, and a drain conduit leading from the discharge portion of the sump, said discharge portion being of such depth or height that when the roof is floating on liquid in the tank the sump projects downwardly a substantial distance below the underside of the roof and when the roof approaches its lowermost position the discharge portion of the sump comes into engagement with the bottom of the tank and exerts pressure on the limber portion of the roof in a direction to flex said limber portion upwardly, thereby decreasing the distance the sump projects downwardly from the roof and also decreasing the slope of the bottom of the sump.

2. The combination of a tank adapted to hold liquid, a floating roof in said tank constructed and arranged so that when the tank is empty the weight or load of the major portion of the area of the roof is supported directly by the bottom of the tank, a sump on said roof, a collapsible pipe drain suspended from said roof and adapted to lie on the tank bottom when the roof is in its lowermost position, the upper portion of said drain being formed by a swing pipe that swings in an are about a horizontal axis when the roof moves upwardly and downwardly due to variation in the level of the liquid on which the roof floats, and a connecting hose projecting laterally from the upper end of the swing pipe and having its opposite ends rigidly connected to the swing pipe and to the sump so that the rocking movement of the swing pipe during the rise and fall of the roof will twist or rotate said hose on its longitudinal axis, said hose being of such length that when the roof is at rest on the bottom of the tank the hose is disposed in the form of a single loop which lies Wholly at one side of a straight line extending between the points of attachment of the hose to the swing pipe and to the sump.

3. The combination of a tank adapted to hold liquid, a floating roof in said tank adapted to move downwardly and come to rest on the bottom of the tank when the tank is being emptied, a pipe drain for said roof suspend ed from the underside of same and comprising members that lie on the bottom of the tank when the roof is in its extreme lower position, an elongated, trough like sump having a shallow intake end that communicates with the top surface of the roof and a deep discharge end from which said pipe drain leads, a limber portion on the roof that carries said sump and maintains the bottom of the sump in a downwardly inclined position and the discharge end of the sump at a level which is a substantial distance below the underside of the roof when the roof is floating on liquid in the tank, the above mentioned limber portion of the roof being located directly above said pipe drain, and a means that coacts with said limber portion when the roof moves to its lower most position on the bottom of the tank, to raise the discharge end of the sump relatively to the roof and also maintain the limber portion of the roof in such a position that said limber portion exerts no weight or load on the members of the pipe drain which lie on the bottom of the tank.

4. The combination of a tank adapted to hold liquid, a floating roof in said tank constructed and arranged so that when the tank is empty the weight or load of the major portion of the area of the roof is supported directly by the bottom of the tank, at least a portion of the roof normally contacted by the liquid in the tank being limber, a drain suspended from the underside of the roof in the zone of the said limber portion of the roof and comprising members that lie on the tank bottom when the roof is in its lowermost position, a supporting means for the limber portion of the roof disposed so that as the roof comes to rest on the bottom of the tank said supporting means flexes the limber portion of the roof upwardly and maintains it in a position where said limber portion exerts no weight or load on parts of the drain which are then resting on the bottom of the tank, and an elongated, trough like sump carried by the said limber portion of the roof and attached to said drain, said sump having a bottom that slopes downwardly and side walls that increase in depth from the intake end to the discharge end of the sump, the discharge end of the sump being of such height or depth that it comes into engagement with the tank bottom before the roof fully comes to rest on the bottom of the tank, thereby raising the discharge end of the sump for the purpose described.

References Cited in the file of this patent UNITED STATES PATENTS 338,848 Lecouteux Mar. 30, 1886 1,668,792 Wiggins May 8, 1928 1,761,700 Bailey June 3, 1930 1,801,172 Patterson Apr. 14, 1931 1,994,478 Kuetfer Mar. 19, 1935 2,321,058 Wiggins June 8, 1943 FOREIGN PATENTS 623,853 Great Britain May 24, 1949 

